The SCOBY: Bill Bond, of Bucha Bill Raw Kombucha, shows off the "symbiotic colony of bacteria and yeast" in his fermented tea. The microorganisms of the SCOBY convert the sweetened tea into the fizzy elixir.

Peggy TurbettThe Plain Dealer /Landov

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Originally published on October 1, 2013 10:34 am

Chances are, you've seen it in your local grocery store. Maybe you've even mustered the courage to taste it — or at least take a whiff.

Once mostly a product of health food stores and hippies' kitchens, kombucha tea is now commercially available in many major grocery stores.

And people aren't necessarily scooping it up for its flavor. Its taste has been described as somewhere between vinegar soda and carbonated apple cider.

Many folks are banking on the potential health benefits of kombucha, including disease prevention, energy improvement and perhaps even turning back the clock and inhibiting aging.

"I've seen claims that kombucha might help kill cancer, is a powerful detoxifier, even a fountain of youth," says Monica Reinagel, a nutritionist and creator of the podcast Nutrition Diva.

Sound fantastical? Well, it probably is.

The bottom line is that we know very little about kombucha and how it may affect health.

"There is really very little evidence to support any kind of claims about kombucha tea," says Andrea Giancoli, spokesperson for the Academy of Nutrition and Dietetics. "So we don't know if it does anything at all."

Nevertheless, most kombucha drinks contain live bacteria. And evidence is mounting that friendly bacteria or probiotics aide digestion and possibly even strengthens the immune system.

These good bugs "actually live inside of us and help digest our food, digesting particles we can't digest on our own," nutritionist Reinagel says. "And they actually produce certain nutrients for us, which is a very nice trick."

Kombucha was popular back in the early '90s, when health-minded consumers produced the tea in their home kitchens. Many HIV-positive individuals consumed it in hopes of boosting their immune systems.

The process of making kombucha is fairly simple. Black or green tea is sweetened with sugar. A concoction of bacteria and yeast is added. The mixture is then fermented in a glass or ceramic container for at least a week.

During this time, microbe production speeds up as the bacteria feast on the added sugar, grow and multiply. The end result looks like a rubbery disc that forms on top of the tea, called the SCOBY, or "symbiotic colony of bacteria and yeast."

It's a thriving colony of microorganisms — billions of them, converting sugar into vinegar and other aromatic compounds. The sheer number of bacteria makes it very difficult to know for sure if the concoction includes only the friendly, good bacteria.

One of the most popular brands of kombucha tea, GT's Kombucha, sells millions of bottles a year. Officials say they test their tea and know it contains at least two important strains of good bacteria.

But that may not be the case for all products now available in supermarkets.

And if you brew it at home, dietitian Giancoli has a warning: "You've got to have really very sanitary conditions and know what you're doing." Otherwise, she says, your tea could get contaminated by not so friendly — or even harmful — bacteria.

In stores, the bottled versions are produced in carefully controlled environments and are likely safe. So if you like the idea of kombucha and if it makes you feel better or more energetic, then there's probably "no harm" in drinking it, nutritionist Reinagel says.

As for the extraordinary health claims — we'll just have to wait until researchers test them out.

Copyright 2013 NPR. To see more, visit http://www.npr.org/.

Transcript

STEVE INSKEEP, HOST:

Another hope for good health that's becoming more and more popular is kombucha, which is a fermented brew of sweetened tea and bacteria. Consumers are hoping the drink will help them fight off disease, improve energy and even inhibit aging.

NPR's Patti Neighmond looks at what we do and do not know about kombucha.

PATTI NEIGHMOND, BYLINE: The bottles are artsy and colorful, the flavors varied; citrus, watermelon, ginger. And the taste, well, acquired.

BRIAN SMITH: For me it's sort of like a vinegar soda, in a way. Like it has like an effervescence to it.

NEIGHMOND: Brian Smith gets his kombucha tea at a local grocery store in Washington, D.C., So does Erin Upton-Cosulich.

ERIN UPTON-COSULICH: The taste is a little bit like beer, kind of tangy and a little bit sweet.

NEIGHMOND: Kombucha is a mixture of black or green tea, sugar, yeast and bacteria. And consumers like Annie Sprengelmeyer say it just makes them feel better.

ANNIE SPRENGELMEYER: It gives you a little bit of a different kind mind clearing. For me it just kind of wakes me up.

NEIGHMOND: Lots of kombucha drinkers describe a similar energy boost or sense of well-being, but bottom line, we just don't know very much about kombucha. And some of the benefits touted, says nutritionist Monica Reinagel, go way too far.

MONICA REINAGEL: I've seen claims that kombucha will help cure cancer, that it's a powerful detoxifier, that it's the fountain of youth.

ANDREA GIANCOLI: There is really very little evidence to support any kind of claims of kombucha tea. We don't know if it does anything at all.

NEIGHMOND: But because most kombucha drinks contains live bacteria, there could be certain health benefits. Evidence is mounting that friendly bacteria or probiotics aid in digestion and possibly even strengthen the immune system.

Nutritionist Monica Reinagel.

REINAGEL: They actually live inside of us and they help digest our food. They actually produce certain nutrients for us, which is a very nice trick.

NEIGHMOND: In the early '90s, kombucha was made in home kitchens. First, black or green tea was sweetened with sugar, then a concoction of bacteria and yeast added. The mixture was fermented for at least a week to speed up production of the bacteria, which took the form of a rubbery layer of goop on top of the tea.

REINAGEL: If you've ever left a cup of coffee on the kitchen counter and gone away for vacation, and come back later and found a little layer of mold on the top of your coffee, that's kind of what it looks like.

NEIGHMOND: That goop is actually a thriving colony of bacteria - billions of them, so it's really difficult to know whether they include the desired friendly bacteria or not.

One of the most popular brands of kombucha tea, GT's Kombucha, sells millions of bottles a year. Officials say they test their tea and know it contains at least two important strains of good bacteria.

But that may not be the case for all products now available. And if you brew it at home, dietitian Giancoli has a warning.

GIANCOLI: You've got to really have very sanitary conditions and know what you're doing.

NEIGHMOND: If you don't, your tea could get contaminated by not so friendly harmful bacteria.

In stores, the bottled versions are produced in carefully controlled environments. So if it makes you feel better, nutritionist Reinagel says there's probably no harm in drinking it.